The grades on a chemistry midterm at Springer are normally distributed with $\mu = 66$ and $\sigma = 3.0$. Vanessa earned a $72$ on the exam. Find the z-score for Vanessa's exam grade. Round to two decimal places.
Solution: A z-score is defined as the number of standard deviations a specific point is away from the mean We can calculate the z-score for Vanessa's exam grade by subtracting the mean $(\mu)$ from her grade and then dividing by the standard deviation $(\sigma)$ $ { z = \dfrac{x - {\mu}}{{\sigma}}} $ $ { z = \dfrac{72 - {66}}{{3.0}}} $ ${ z \approx 2.00}$ The z-score is $2.00$. In other words, Vanessa's score was $2.00$ standard deviations above the mean.